function [X_norm, mu, sigma] = featureNormalize(X)

    mu = mean(X); % dimension = 1 * 2;
    sigma = std(X); % dimension = 1 * 2;
    X_norm = (X - repmat(mu, size(X, 1), 1)) ./ repmat(sigma, size(X, 1), 1);
end
